[Cycles] High CPU usage when rendering with GPU

Hi All,

Does anyone else also face this issue? I’m not talking about preparation phase when CPU is heavily used but about the ray tracing phase.
It’s much worst than rendering on CPU, my computer freezes, mouse is very laggy, all cores are utilized in 99-100%…
It’s almost not possible to work in Node Editor (with 3d view type set to “render”) if GPU computing is enabled…
I’m using Fedora 16 and NVidia GTX 275.

With a MinGW64 Win build it is similar but at the moment not using cycles i have the same issue when using the skin modifier. But using a GTX 550Ti.

Fedora 15 :).
While there are a lot of progs out which cause 98% load on each of my 2 Athlon cores, blender without cycles on CPU included, UI usually is quite fast and agile.
Not when GPU is used for rendering - that causes UI locks, unresponsiveness. And that’s expected somehow. Also, might be that your cores are preparing or receiving data from GPU during render, hence high loads, but that’s not the reason behind UI lags imo. Just that thing which renders screen, UI changing parts, is kept very bussy. Mouse for X is driven by nv driver also afaik.
Then again, might depend on what’s being rendered, but i’m pretty sure, for me, there’s no such a high CPU load while rendering on GPU (one nv560, 2Gb; lags used to be much worse on 9800, i really could not work with node tree while rendering).

Any flash videos behind the scenes while rendering? That stuff is ridiculously broken, doing all the weirdest things possible, high CPU loads included. Have you checked what processes use CPU at the high loads, is it blender only? Same render compared on v2.62? Recent nvidia driver change? Any system-wide updates (seen 3 win pcs broke recently because of interrupted ones, recent linux distros are not much better in that department)? Anything suspicious in syslog?

I’ve gone through some 3 different buildbot blender builds during this month and can’t say rendering is taking much more power out of my pc.

CPU load on 2 cores with rendered 3d view looks like this:
~120-150% blender
~50-60% gnome-shell
~5-25 Xorg
NVIDIA Driver Version: 295.59
I’ll switch to kde and then check again.

After switching to LXDE it’s looks very similar:
~120-160% blender
~20-60% Xorg
It’s better but just a little bit.

Unfortunately - true.
Depends on scene complexity heavily. While it’s perfectly fine with cube and sphere on a plane :)(preview render set to 4000 passes),do whatever you like; if there are some 20 Alt duplicated planes with particle objects on them (kinda like grass - 600 particles, 24 planes, dupliobjects with some 12 faces ) system goes to almost halt. 2 cores at 99%, GPU rendering does the rest - say ‘hello’ to mouse clicks or moves; any click takes some 20 seconds to respond. I did not notice this earlier since i was more interested on render speed gain after changed GPU, so was passively watching it render only.
Did try all available old builds - oldest vas 2.58.1 r39228 - same game. Two default Suzies render lightning fast, can manipulate 3dview, material nodes; duplicated object file brings to ‘sit back and watch’ mode.
So it looks like it is as it is.